Beamsteering is the angular positioning of the main lobe of a radiation pattern. This allows for greater discrimination in favor of a desired signal from a point-like source in the far field of the antenna, for sensing or information transmission and reception. When it is required to steer the beam of a planar array antenna over a limited range in two dimensions around an array axis which is perpendicular to the plane of the array, it becomes difficult to fit each element with a variable phase shifter or transceiver module, and incorporate the elements into the feed structure as would be devised in the conventional approach. This is especially true where the wavelengths involved are small, because the array elements and spacings scale with wavelength (must be in the order of half wavelength) whereas feed lines and phase shifters take up additional room and do not completely scale with wavelength, especially transceiver modules. As such, the phase shifters and transceiver modules become expensive for short wavelengths, e.g. millimeter-waves, so it is desirable to use as few of them as possible to achieve the desired beam control.
Therefore there is a need for a method and apparatus for feeding a circular antenna array, that obviates or mitigates one or more limitations of the prior art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.